Electrode feed mechanism for searchlights



Dec. 13, 1938. w. A. PENNOW 7 2,140,372

ELECTRODE FEED MECHANISM FOR SEARCHLIGHTS Filed Nov. 27, 1934 2Sheets-Sheet l 3 6 Vb/fag-e Cal/ WITNESSES: INVENTOR J' MY/As fl/ ennow.

Dec. 13,1938. w. A. PENNOW 2,140,372

ELECTRODE FEED MECHANISM FOR SEARCHLIGHTS Filed Nov. 27, 1934 2.Sheets-Sheet 2 L? 2 I /9 2 7 'IJ'HIIIII VIA l5 /8 24 Wm //M\\\ 26 25Phofo 53 I/b/Iaye (Te/K I I T 35 WITNESSES: INVENTOR fdw I /4/////5/7/%fl/70W Patented Dec. 13, 1938 UNITED STATES ELECTRODE FEED MECHANISMFOR SEARCHLIGHTS Willis A. Pennow, Lakewood, Ohio, assignor toWestinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., acorporation of Pennsylvania Application November 27, 1934, Serial No.

3 Claims.

My invention relates, generally, to are controlling devices and moreparticularly, to devices for controlling the feeding operation of anelectrode which may be used in searchlights and are lighting devices ingeneral.

Heretofore, it has been the practice to control the feeding operation ofpositive electrodes in high-intensity arc searchlights by means of feedmechanisms in the form of ratchet devices and.

the like, the functioning of which are controlled by thermostaticdevices responsive to radiant energy produced by the crater or tip ofthe positive electrode and arranged to maintain the tip or crater of thepositive electrode at or near the focal center of the reflector,.orother predetermined position.

It has been found that the devices of the prior art are deficient inmany ways as they do not function to accurately control or constantlymaintain the tip of the positive electrode in the desired position, donot provide a smooth feeding action, are complicated in constructionwhich requires constant maintenance and are adversely affected bychanges in temperature.

It is the object of my invention generally stated, to provide a feedingdevice for positive electrodes in arc searchlights which shall be ofsimple construction, economical to manufacture and install, which shallbe efficient and accurate in operation, which will feed the electrode ina smooth manner and be capable of ready adjustment and which shall notbe adversely affected by temperature changes.

The object of my invention, more specifically stated, is to provide forfeeding apositive are light electrode in accordance with the position ofthe tip or crater thereof.

Another object of my invention is to provide for utilizing aphoto-voltaic cell or device for maintaining the tip or crater of anelectrode at a predetermined location with respect to the reflector orlens with which it is used.

A still further object of my invention is to provide for automaticallycontrolling the feeding operation of an electrode by means of alight-responsive voltage-generating device responsive to the radiantenergy of the electrode tip.

Another object of my invention is to provide for automaticallymaintaining the tip of an electrode at a predetermined position withrespect to the reflector or lens of an-arc light by utilizing aself-energizing system or device responsive to electro magneticradiation produced at the tip,

of the electrode.

These and other objects of my invention will become evident from-areading of the following detailed description in conjunction with thedrawings in which:

Figure l is a diagrammatic view of a feeding I system for the positiveelectrode of an are search-- light embodying the principal features ofmy invention,

Fig. 2 is a diagrammatic view of a modification of the system of Fig. 1and Fig. 3 is a diagrammatic view of another embodiment of my invention.

In practicing my invention in its most elementary and generic form,feeding mechanism for the electrode regardless of the particular typeused, is controlled by a voltage-generating device which may take theform of a photo-voltaic cell which is so positioned with respect to thetip of the electrode to be controlled as to function only when theelectrode tip deviates from a predeter- 1 mined normal position, thatis, when the electrode burns away so that the tip is no longer at ornear the focal center vof the reflector of the searchlight or any otherpredetermined position, the photo-voltaic cell is subjected to theradiant energyproduc'ed at the electrode tip and functions to cause thefeeding mechanism to move or advance the electrode until the tip isagain in normal position. The functioning of the photo-voltalc cell iscontrolled by means of suitable baffles,

shields or the like placed between it and the electrode tip.

Referring now to Fig. 1 of the drawings, there is illustrated inschematic form one concrete em bodiment of my invention as it may beapplied for controlling the feeding operations of the positive electrodeof an arc searchlight. The numeral Ill designates the negative electrodeand II the positive electrode. The negative electrode Iii may besupported in any suitable well known manner and its feeding operationscontrolled by the feed rolls I2, which may be driven to control thestriking of the arc and thereafter to feed the electrode to the arc inany suitable manner well known in the art.

In this instance, the feeding mechanism for the positive electrode II isshown generally at I3 and provides for both feeding and rotating theelectrode. The feedingmechanism I3 comprises a sleeve I4 on whichoppositely disposed feed rolls I5 and I6 are supported. As will bereadily under stood, the sleeve I4 may be rotatably supported in anysuitable manner on the head of the searchlight (not shown), and may berotated by any suitable mechanism which may or may not constitute a partof the feeding mechanism for the negative electrode.

In order to provide for actuating the feed rolls I5 and I6 to feedtheelectrode II forwardly as I When the sleeve I4 is rotated, the gearelement I! will also rotate and there will be no relative movementbetween it and the pinion 23 so that the feed rolls will not be drivenin either direction. This operation merely causes the feed rolls to berevolved about the axis of the electrode, thereby rotating the electrodewithout feeding it in either direction. It is apparent, however, thatrotation of the feed rolls occurs whenever the gear I! is heldstationary to cause relative movement between the pinion 23 and thetoothed portion 24.

It is to be understood that the particular type of feed mechanismdescribed has been used for the purpose of illustration only and thatany other suitable device may be used as well.

The feeding mechanism l3 may be actuated in any suitable manner such forexample as by means of the motor 25 which is connected to the sleeve Mby means of beveled gears 26 and 21. As described hereinbefore, themotor 25 may comprise a part of the negative electrode feed mechanism orit may function as a separate element preferably actuating the feedmechanism [3 at a substantially constant speed.

In order to cause the feed mechanism l3 to become operable toactuate'the feed rolls l5 and I6, there is provided a stopping device orpawl 28 in the form of a plunger which, when actuated to the upperposition, engages another toothed portion 29 of the gear I! to hold.itstationary with'respect to the rotating sleeve I4. In this instance, thestopping device 28 is actuated directly by ele'ctromagnet 3|, which maybe energized from the current source comprising conductors 32 and 33. v

In order to control the feeding operations of the positive electrode insuch manner as to maintain the tip 34 thereof at or near the focalcenter of the Searchlight or other predetermined po- -sition, provisionis made for rendering the feed controlling electromagnet 3i responsiveto the position of the electrode tip. In this instance, the energizationof the electromagnet 3i is controlled by means of a suitable relay 35.In order to effect the operation of the relay 35 whenever the electrodetip recedes from a predetermined position, there is utilized alight-sensitive device 35 which is so positioned with respect to theelectrode tip 34 that it controls the operation of relay 35 in responseto the movements of the positive electrode.

In this instance, the light-responsive device 36 is illustrated in theform of a photo-voltaic cell, which functions when the radiant energy ofthe electrode tip is directed upon it to develop a voltage of suflicientmagnitude to operate the relay 35. It is apparent that a photo-voltaicor photovoltage cell of any form may be used for this purpose.

In order to direct the radiant energy from the electrode tip upon thephoto-voltaic cell any suitable means such, for example, as lightbarriers 31 and 38 may be utilized. As shown, when the electrode tip isin the position shown in the drawings, the maximum amount of radiantenergy is permitted to fall upon the cell which causes it to develop itsmaximum voltage to operate the relay 35 to its closed position, therebyenergizing the electromagnet 3| which causes the feed mechanism tofunction to feed the electrode forwardly. As the electrode tip advances,the barriers 31 and 38 reduce the radiant energy which falls upon thecell until a point is reached where the cell no longer is energizedsumciently to develop the required voltage which causes the relay 35 toopen and stop the feeding operation. As soon, however, as the electrodeburns away sufliciently to permit the greater amount of radiant energyto fall upon the cell, the feeding operation is again initiated.

It is also to be understood that any other suitable means may be used todirect the radiant energy from the tip of the positive electrode uponthe cell or device 36, such for example as a lens or the like suitablypositioned between the electrode and the cell.

The electrodes l0 and II are energized in this instance from theconductors 32 and 33 by means of suitable brushes or contact elements 4!and 42, the energizing circuit including the ballast resistor 43.

In view of the foregoing description, it will be apparent that the relay35 and electromagnet 3| function in somewhat the same manner as aregulator, thereby continually advancing the positive electrode as fastas it is consumed, the degree of movement of the electrode beingdependent upon the length of time during which the gear element I1 isheld stationary.

'Referring now to Fig. 2 of the drawings, there is illustrated apositive electrode feeding mechanism in which the photo-voltaic cellprinciple is utilized for directly controlling the speed of the feedingmotor.

' In this instance the positive electrode II is fed by means of rolls 44and 45 and is rotated by a separate pair of rolls 46 and 41. As in thesystem shown in Fig. 1, the rolls 46 and 41 may be actuated by means ofa motor 48 which may or may not constitute a part of the negativeelectrode feeding mechanism. The motor 48 is preferably operated atsubstantially constant speed in order to insure uniform burning of thepositive electrode.

' In this instance the feed rolls 44 and 45 are actuated by a separatevariable speed feed motor 49 connected thereto through gears 5 I.

The feed motor 49 is connected across the source represented byconductors 32 and 33 through a suitable resistor 52 and its speedadjusted so that the positive electrode H is moved forwardly at a speedwhich is'slightly lower than the feeding speed necessary to constantlymaintain the electrode tip at the desired position.

In this instance, the photo-voltaic cell 36 and relay 35 are utilized tocontrol the effectiveness of the resistor 52, and thereby control thespeed of the feed motor 49 by varying the resistance of its armaturecircuit.

As will be readily understood, when the positive electrode tip recedesto the position shown, the photo-voltaic cell develops a maximumvoltage, thereby actuating the. relay 35 to short circuit a portion ofthe resistor 52. This increases the speed of the feed motor to cause theelectrode to be advanced at a higher speed than it is being consumed,thereby moving the tip thereof toward the focal center of the reflectoror to some other predetermined position.

In Fig. 3 there is illustrated another embodiment of my inventionsomewhat similar to that shown in Fig. 1 with the exception that in thisinstance the gear element l'!- of the feeding device I3 is disposed tobe driven by a feed motor ahich'is connected thereto by suitable gearingAs will be readily understood, when the gear element ll'is driven by thefeed motor 53 at the same speed as the sleeve I4 is driven, the feedrolls Ii and Il will not rotate so that the electrode II is not advancedor retracted. As soon, however, as the gear element i1 is caused torotate relative to the sleeve l4, rotation of the feed rolls results.

In this instance, the armature resistor 52 may be adjusted to cause thefeed motor 53 to continually advance the electrode at a slightly slowerspeed than is required to compensate for the burning away of theelectrode tip. When the electrode tip recedes a predetermined distancefrom the desired position, as determined by the adjustment of the lightbarriers 31 and 38, the photo-voltage device 36 will function toenergize the relay 35, thereby shunting the resistor 52 and increasingthe speed of the feed motor II.

The feed motor 53 now functions to advance the electrode II at a fasterrate than its rate of consumption and returns the tip to the normal ordesired position at which point the resistor 52 is again rendered fullyeffective and the speed of the feed motor reduced.

It is, therefore, apparent that with this arrangement, the positiveelectrode is being continuously advanced, the photo-voltage device andrelay 35 again functioning in somewhat the same manner as a regulator topositively maintain the tip of the electrode at or near the desiredposition by means of a smooth and positive feeding motion.

Furthermore, it is evident that therelative positions of the electrodetip, barriers 31 and 38 and the photo-voltage device 36 may be such thata very sensitive form of feeding device is provided, so that there isvery little deviation of the electrode tip from the desired positionwhich greatly increases the steadiness of the arc and the efficiency ofthe lamp.

While armature control of the feed motor has been illustrated in bothFigs. 2 and 3, it is apparent that the application of my photo-voltagecontrol is not necessarily limited to this particularform of motorcontrol, since the relay 35 may beutilized to control the functioning ofother forms of motor speed controlling devices well known in the motorcontrol art.

In view of the foregoing, it is apparent that I have provided anelectrode feeding mechanism which is of simple nature, and which hasmany desirable features over electrode feeding mechanisms of the priorart. It is apparent that by the use of the photo-voltaic cell. nooutside source of voltage is necessary and that the control isunaffected by changes in temperature, since its function is dependententirely upon the radiant energy produced at the tip of the electrode.

While the invention has been illustrated and described in connectionwith are searchlights, it is apparent that it may be applied to otherkinds of arc lights where it is desired to constantly and accuratelymaintain the tip of the electrode at a predetermined position.

It may be stated in conclusion that while the illustrated examplesconstitute practical embodiments of my invention, I do not wish to limitmyself strictly to the exact details herein illustrated, sincemodifications in the same may be made without departing from the spiritof the invention as defined in the appended claims.

I claim as my invention:

1. In a system for controlling the; feeding of electrodes in arccircuits having cooperatingelectrodes comprising an electrode which, isto be maintained in a predetermined position, an electrode holder, feedrolls mounted on said electrode holder and engaging the electrode toproduce rotation of the electrode about its longitudinal axis when theelectrode holder is rotated, means for continuously rotating theelectrode holder,

a rotatable element mounted on said electrode tion of the electrode inthe arc while the arc is burning, and means responsive to the positionof the electrode for controlling the speed of rotation of said means forcontinuously rotating said rotatable element to thereby vary the rate offeed of the electrode in response to predetermined positioning of saidelectrode.

2. In a system for controlling the feeding operation of electrodes inarc circuits having cooperating electrodes comprising an electrode thearc tip of which is to be maintained in a predetermined position, anelectrode holder, feed rolls mounted on said. electrode holder andengaging the electrode to produce rotation of the electrode about itslongitudinal axis when the electrode holder is rotated, means forcontinuously rotating the electrode holder, a rotatable element mountedon said electrode holder, means for continuously rotating said rotatableelement, means responsive to the differential movement between saidrotatable element and said electrode holder for rotating said feed rollsto continuously feed the electrode toward the arc while the arc isburning, means for varying the speed of rotation of said means forcontinuously rotating said rotatable element, a light responsive voltagegenerating element, and means whereby said light responsive elementcontrols said speed varying means, said light responsive element beingso positioned as to be affected by the light from said arc'tip' when itmoves from said predetermined position while the electrode is arcing.

3. In a system for controlling the feeding operations of electrodes inarc circuits having coopcrating electrodes, in combination, anelectrode, an electrode holder, feed rolls mounted on said electrodeholder and engaging the electrode to produce rotation of the electrodeabout its longitudinal axis when the electrode holder is rotated, meansfor continuously rotating said electrode holder at a substantiallyconstant speed, a rotatable member mounted on said electrode holder, avariable speed motor for rotating said rotatable member continuously,means responsive to the differential movement between said electrodeholder and said rotatable member for'rotating said feed rolls tocontinuously feed said electrode, means for so controlling thedifferential speed between said electrode holder and said rotatablemember as to provide a predetermined rate of feed of said electrode,alight responsive cell so situated as to be affected by the light fromthe electrode upon predetermined movement of the tip of the electrodefrom a predetermined position while there is an are burning between thecooperating electrodes, means for increasing the speed of said variablespeed motor and means whereby said light responsive cell controls saidspeed increasing means.

WILLIS A. PENNOW.

